IPv6 solves the IPv4 public address depletion problem by providing a
huge address space. The business benefit of moving to IPv6 is that mobile cell
phones, personal data assistants (PDAs), automobiles, appliances, and even
people can be assigned multiple globally reachable addresses. The growth of the
devices connected to the Internet and the software that these devices run can
proceed without restraint and without the complexity and cost of having to
operate behind NATs.